V210 issue fix + correct packing

internal/generator/cpu_patterns.go

@@ -127,13 +127,14 @@ func movingSquarePatch(baseColor baseColorFunc) FrameRenderer {
 }
 
 func renderBasePattern(dst []byte, width, height int, baseColor baseColorFunc) error {
+	stride := V210LineSize(width)
 	for y := 0; y < height; y++ {
 		for x := 0; x < width; x += 6 {
 			var pixels [6]YCbCr10
 			for i := range pixels {
 				pixels[i] = baseColor(x+i, y, width, height)
 			}
-			offset := (y*width + x) / 6 * 16
+			offset := y*stride + x/6*16
 			packV210Block(dst[offset:offset+16], pixels)
 		}
 	}